Bacillus thuringiensis와 고삼추출물 혼합처리에 의한 파밤나방 방제효과

Combination Effects of Bacillus thuringiensis and Sophora Extract on Spodoptera exigua

본 연구는 난방제 해충인 파밤나방을 농가에서 효과적으로 방제하기 위해 Bacillus thuringiensis와 고삼추출물 혼합처리에 의한 살충효과를 실내 포트 및 포장 실험을 통해 조사하였다. 실내 포트 실험에서 BT를 농도별($1{\times}10^5$, $1{\times}10^6$, $1{\times}10^7cfu\;mL^{-1}$)로 처리하였을 때 파밤나방의 살충율은 27.5%, 51.3%, 92.5%로 농도가 높아질수록 살충율이 증가하였다. BT ($1{\times}10^5$, $1{\times}10^6$, $1{\times}10^7cfu\;mL^{-1}$)와 0.033% 고삼추출물 혼합처리구의 살충율은 98.8%, 88.8%, 91.3%로 BT 단독처리보다 BT+고삼추출물 혼합처리구가 높은 살충율을 나타냈으며, 혼합된 BT의 농도가 낮을수록 살충율 증가가 높았다. 각 처리별 파밤나방의 식이저해 효과는 BT의 농도가 높아질수록 우수한 것을 확인하였다. 또한 포장 실험에서도 실내포트 실험과 유사하게 BT 단독처리구(14.4%, 26.7%, 66.7%)보다 고삼추출물 혼합처리구가 높은 살충율(72.2%, 67.8%, 61.1%)을 나타냈으며 식이저해효과 또한 실내실험과 유사한 결과를 나타냈다. 따라서 농가에서 파밤나방을 효과적으로 방제하기 위해서는 BT 단독처리보다 0.033% 고삼과 BT($1{\times}10^5cfu/ml$)를 혼합하여 처리하는 것이 효과적일 것으로 사료된다.

This study was conducted to identify the insecticidal effect of a mixture of sophora extract and Bacillus thuringiensis against Spodoptera exigua on potted chinese cabbage in both laboratory and plastic house condition. In laboratory condition, mortality of larvae by BT ($1{\times}10^5$, $1{\times}10^6$, $1{\times}10^7cfu\;ml^{-1}$) alone was 27.5%, 51.3% and 92.5%, respectively, which was depend upon concentration of BT. Control efficacy of the mixture of BT and sophora extract was 98.8%, 88.8% and 91.3% which was higher than BT treatment only. The mixture of sophora and lower BT concentration was showed more increase of control efficacy. Anti-feedant effect by BT was depend on concentration of BT. At field experiment, the mixture of BT and sophora extract appeared higher mortality (72.2%, 67.8%, 61.1%) than BT treatment only (14.4%, 26.7%, 66.7%) similar with laboratory experiment. The mixture was less affected by environmental condition at field than BT only. Therefore, for effective control of beet armyworm without possibility to develop resistance against BT at farm, treatment of the mixture of sophora extract (0.033%) and BT ($1{\times}10^5cfu\;ml^{-1}$) would be considered more effective than BT treatment only.